Fix mobile launch with a saved workspace

packages/app/src/app/h/[serverId]/index.tsx

@@ -1,10 +1,39 @@
-import { Redirect, useLocalSearchParams } from "expo-router";
-import { buildOpenProjectRoute } from "@/utils/host-routes";
+import { Redirect } from "expo-router";
+import { useHostRouteServerId } from "@/navigation/host-route-context";
+import {
+  resolveHostIndexRoute,
+  resolveWorkspaceSelectionStatus,
+} from "@/navigation/host-runtime-bootstrap";
+import { StartupSplashScreen } from "@/screens/startup-splash-screen";
+import { useHasHydratedWorkspaces, useWorkspaceExists } from "@/stores/session-store-hooks";
+import {
+  useIsLastWorkspaceSelectionHydrated,
+  useLastWorkspaceSelection,
+} from "@/stores/navigation-active-workspace-store";
 
 export default function HostIndexRoute() {
-  const params = useLocalSearchParams<{ serverId?: string }>();
-  const serverId = typeof params.serverId === "string" ? params.serverId : "";
-  if (!serverId) return null;
-  // COMPAT(hostRootOpenProjectRoute): added 2026-06-11, remove after 2026-12-11.
-  return <Redirect href={buildOpenProjectRoute()} />;
+  const serverId = useHostRouteServerId();
+  const workspaceSelection = useLastWorkspaceSelection();
+  const isWorkspaceSelectionLoaded = useIsLastWorkspaceSelectionHydrated();
+  const workspaceSelectionWorkspaceId =
+    workspaceSelection?.serverId === serverId ? workspaceSelection.workspaceId : null;
+  const hasHydratedWorkspaces = useHasHydratedWorkspaces(serverId);
+  const workspaceSelectionExists = useWorkspaceExists(serverId, workspaceSelectionWorkspaceId);
+
+  if (!serverId || !isWorkspaceSelectionLoaded) {
+    return <StartupSplashScreen />;
+  }
+
+  return (
+    <Redirect
+      href={resolveHostIndexRoute({
+        serverId,
+        workspaceSelection,
+        workspaceSelectionStatus: resolveWorkspaceSelectionStatus({
+          hasHydratedWorkspaces,
+          workspaceExists: workspaceSelectionExists,
+        }),
+      })}
+    />
+  );
 }

packages/app/src/navigation/host-runtime-bootstrap.test.ts

@@ -2,6 +2,7 @@ import { describe, expect, it, vi } from "vitest";
 import {
   resolveStartupBlocker,
   resolveStartupNavigationReady,
+  resolveHostIndexRoute,
   resolveStartupRoute,
   shouldRunStartupGiveUpTimer,
   startHostRuntimeBootstrap,
@@ -250,7 +251,7 @@ describe("resolveStartupRoute", () => {
     ).toEqual({ kind: "splash" });
   });
 
-  it("restores the saved workspace only after the host registry proves the host exists", () => {
+  it("enters the host boundary for saved workspace restore after the host registry proves the host exists", () => {
     expect(
       resolveStartupRoute({
         ...baseIndexInput,
@@ -258,7 +259,7 @@ describe("resolveStartupRoute", () => {
         workspaceSelection: { serverId: "server-1", workspaceId: "workspace-a" },
         workspaceSelectionStatus: "exists",
       }),
-    ).toEqual({ kind: "redirect", href: "/h/server-1/workspace/workspace-a" });
+    ).toEqual({ kind: "redirect", href: "/h/server-1" });
   });
 
   it("does not restore a saved workspace after workspace hydration proves it is missing", () => {
@@ -357,3 +358,55 @@ describe("resolveStartupRoute", () => {
     ).toEqual({ kind: "redirect", href: "/welcome" });
   });
 });
+
+describe("resolveHostIndexRoute", () => {
+  it("restores the remembered workspace when the host index opens for the same host", () => {
+    expect(
+      resolveHostIndexRoute({
+        serverId: "server-saved",
+        workspaceSelection: { serverId: "server-saved", workspaceId: "workspace-a" },
+        workspaceSelectionStatus: "exists",
+      }),
+    ).toEqual("/h/server-saved/workspace/workspace-a");
+  });
+
+  it("keeps restoring a remembered workspace before the host workspace list hydrates", () => {
+    expect(
+      resolveHostIndexRoute({
+        serverId: "server-saved",
+        workspaceSelection: { serverId: "server-saved", workspaceId: "workspace-a" },
+        workspaceSelectionStatus: "unknown",
+      }),
+    ).toEqual("/h/server-saved/workspace/workspace-a");
+  });
+
+  it("opens global project selection when the remembered workspace is proven missing", () => {
+    expect(
+      resolveHostIndexRoute({
+        serverId: "server-saved",
+        workspaceSelection: { serverId: "server-saved", workspaceId: "workspace-a" },
+        workspaceSelectionStatus: "missing",
+      }),
+    ).toEqual("/open-project");
+  });
+
+  it("opens global project selection when the remembered workspace belongs to another host", () => {
+    expect(
+      resolveHostIndexRoute({
+        serverId: "server-saved",
+        workspaceSelection: { serverId: "server-other", workspaceId: "workspace-a" },
+        workspaceSelectionStatus: "exists",
+      }),
+    ).toEqual("/open-project");
+  });
+
+  it("opens global project selection when no workspace is remembered", () => {
+    expect(
+      resolveHostIndexRoute({
+        serverId: "server-saved",
+        workspaceSelection: null,
+        workspaceSelectionStatus: "unknown",
+      }),
+    ).toEqual("/open-project");
+  });
+});

packages/app/src/navigation/host-runtime-bootstrap.ts

@@ -174,6 +174,20 @@ export function resolveWorkspaceSelectionStatus(input: {
   return input.hasHydratedWorkspaces ? "missing" : "unknown";
 }
 
+export function resolveHostIndexRoute(input: {
+  serverId: string;
+  workspaceSelection: ActiveWorkspaceSelection | null;
+  workspaceSelectionStatus: WorkspaceSelectionStatus;
+}): Href {
+  if (
+    input.workspaceSelection?.serverId === input.serverId &&
+    shouldRestoreWorkspaceSelection(input)
+  ) {
+    return buildHostWorkspaceRoute(input.serverId, input.workspaceSelection.workspaceId);
+  }
+  return buildOpenProjectRoute();
+}
+
 function isIndexPathname(pathname: string) {
   return pathname === "/" || pathname === "";
 }
@@ -198,12 +212,11 @@ function resolveReadyIndexStartupRoute(input: ResolveIndexStartupRouteInput): St
     shouldRestoreWorkspaceSelection(input) &&
     hostExists(input.hosts, input.workspaceSelection.serverId)
   ) {
+    // Native cold launch must enter the host boundary first. The host index
+    // owns workspace restore after its local dynamic params exist.
     return {
       kind: "redirect",
-      href: buildHostWorkspaceRoute(
-        input.workspaceSelection.serverId,
-        input.workspaceSelection.workspaceId,
-      ),
+      href: buildHostRootRoute(input.workspaceSelection.serverId),
     };
   }